This invention relates primarily to a file memory unit having a head positioning mechanism, the memory unit being for example a magnetic disk memory unit with the ability of absorbing the vibration and impact attributable to the positioning operation for the achievement of fast and accurate head positioning.
Magnetic disk memory units have a dominant role as file memories in information processing systems in recent years. The file memory system is under way of innovation for the enhancement of compactness, recording density, capacity and access time. A trend in the magnetic disk memory unit is the prevalence of compact magnetic disk memory units which drive magnetic disks of eight inches, five inches or three inches in diameter. These magnetic disk memory units are intended to share the physical standard (dimensions, etc.) and electrical interface with flexible disk memory units, and therefore they must be extremely compact and yet capacious by high-density recording.
Magnetic disk memory units with a relatively low recording density, low capacity and low access speed employ a stepper motor head drive system, while those with a high recording density, high capacity and high access speed employ a drive system using a voice coil motor which operates by the principle of a loud speaker. A magnetic disk memory unit in general has a spindle which provides an accurate, rotational support for a plurality of magnetic disks, a magnetic head which records or retrieves information on a concentric track on the disk surface, and a head positioning mechanism which brings the magnetic head fast and accurately to an intended track. Head positioning systems include one in which the head positioning mechanism is combined with an auxiliary position sensing mechanism by which the head position is detected during the positioning operation, and another one in which one or more magnetic disks have a prerecorded reference position track (servo track) which by being read provides the accurate head position during the positioning operation.
In order for the magnetic disk file memory to have an enhanced capacity and the ability of fast and accurate information recording and retrieval, the track density is increased or track width is narrowed to achieve an increased recording density on each disk surface and a powerful voice coil actuator is used for moving and repositioning the magnetic head in thedisk radial direction quickly and accurately. The track seek operation by the voice coil actuator induces an enormous shock to the stator supporting member, imposing the adverse effect on the head positioning accuracy. The following are conventional techniques for getting rid of this problem.